@amw88 This is going to be long, so apologies in advance. Also, it looks like you're in the maintenance phase, so may not be as relevant as it's purely about cutting, but hopefully someone may find it helpful!
Answer:
First, if you're interested in learning more on cutting and muscle gain/loss, I highly recommend
this guy's articles, as well as browsing
r/fitness. They have a larger community and so have a bit more detailed answers on cutting and bulking, plus cite research that backs it up.
That being said, I'll take a shot at answering your question (based on my understanding). In terms of muscle loss during a cut, it depends on a lot of factors. Most important is your body fat percentage at the time of your cut, but also important is your level/type of activity during your cut, the level of cut that you're doing (e.g., 10%, 20%, etc.), and your macros that you eat while cutting. While I won't say that it's impossible to maintain all of your muscle while cutting, it's unlikely unless you are starting with a high body fat percentage, maintain an effective lifting regime while cutting, and keep up higher levels of protein in your diet.
The reason is, at a very high level, your body will naturally break down both muscle AND fat to supplement energy stores while you're dieting. Especially if you are already at a normal or lower body fat percentage and you're doing a more extreme cut, your body may even prioritize breaking down muscle over fat. The articles I linked should have the more scientific details on actual biology involved.
I like to think of it as the flip side of the sad bulking coin: all of the extra calories that you consume won't go to creating muscle, some will go to fat. There are things that you can do to minimize that, but it's unrealistic to expect that you won't lose any muscle during a cut or gain any fat during a bulk.
This is often why people talk about the importance of high protein on a cut, as well as why some folks go for a slower cut. Both of these can minimize muscle loss, while maximizing fat loss. The prevailing wisdom is that it's impossible to make muscle gains while on a cut (because you have no excess calories from which to build muscle). I prefer
Lyle McDonald's explanation, which is that it's possible if you're an "overfat beginner" (his words), but unlikely otherwise.
For a beginner, though, you don't necessarily have to gain muscle to get stronger. If you are starting from a high body fat percent and have less muscle, you'll also have less muscle loss during your cut.
I know this is getting long, but if I had to give an end take-away, it would be:
don't over-think it. It sounds like what you're doing is working for you and, unless it's been 1 lb. loss steady over more than 5-6 months, you might be able to attribute it to water fluctuation. If you're getting frustrated or curious, though, you may consider incorporating more protein into your diet and upping your calories a bit, and seeing what happens.
If you want more detailed answers on your specific situation, you could try asking on r/fitness (or this sub). You'll need to include more info, though, especially on your lifting routine and examples of your daily food intake.